A piece of ribbon 4200 cm long is cut into 3 parts, B, A and C.
B is 3 times as long as A.
C is 140 cm shorter than A.
Give the answers in cm.
- How much shorter is C than B?
- What is the total length of B and A?
(a)
Choose the shortest length to be 1 u.
Length of C = 1 u
Length of A = 1 u + 140
Length of B = 3 x (1 u + 140) = 3 u + 420
Total length of B, A and C
= 3 u + 420 + 1 u + 140 + 1 u
= 3 u + 1 u + 1 u + 420 + 140
= 5 u + 560
5 u + 560 = 4200
5 u = 4200 - 560
5 u = 3640
1 u = 3640 ÷ 5 = 728
Length of C shorter than B
= 3 u + 420 - 1 u
= 3 u - 1 u + 420
= 2 u + 420
= 2 x 728 + 420
= 1456 + 420
= 1876 cm
(b)
Total length of B and A = 3 u + 420 + 1 u + 140
= 3 u + 1 u + 420 + 140
= 4 x 728 + 560 = 2912 + 560 = 3472 cm Answer(s): (a) 1876 cm; (b) 3472 cm
